1,339 research outputs found
Morphology of Fine-Particle Monolayers Deposited on Nanopatterned Substrates
We study the effect of the presence of a regular substrate pattern on the
irreversible adsorption of nanosized and colloid particles. Deposition of disks
of radius is considered, with the allowed regions for their center
attachment at the planar surface consisting of square cells arranged in a
square lattice pattern. We study the jammed state properties of a generalized
version of the random sequential adsorption model for different values of the
cell size, , and cell-cell separation, . The model shows a surprisingly
rich behavior in the space of the two dimensionless parameters
and . Extensive Monte Carlo simulations for system sizes of
square lattice unit cells were performed by utilizing an
efficient algorithm, to characterize the jammed state morphology.Comment: 11 pages, 10 figures, 3 table
The Okun Misery Index in the European Union Countries from 2000 to 2009
The study is composed of four main parts and a summary. The first part, introduction, discusses various measures of the economic system's efficiency that are used in practice. Part two emphasises that the GDP per capita according to purchasing power parity still remains the most popular among those measures. Further, it presents the ranking of the European Union countries taking that measure into account, the research period being 1999-2009. Part three points out that it is also the level of poverty (misery) that determines the economic system's efficiency. That level can be measured by means of various indicators, among others, the so called HPI-2 index calculated by the UN. It will be the Okun misery index, however, computed as the sum of inflation and unemployment rates that will be presented as an alternative being of interest from the macroeconomic point of view. The ranking of the European Union member states according to that measure in the 2000-2004 and 2005-2009 periods will be provided in part four. The article will end in a summary containing synthetic conclusions drawn from earlier observations.Opracowanie składa się z czterech części zasadniczych i podsumowania. W punkcie pierwszym omówiono różnorodne mierniki sprawności systemu gospodarczego wykorzystywane w praktyce. W części drugiej podkreślono, iż nadal najpopularniejszym z nich jest PKB per capita według parytetu siły nabywczej. Zgodnie z tym miernikiem przedstawiono ranking państw Unii Europejskiej w latach 1999-2009. W punkcie trzecim podkreślono, że o sprawności systemu gospodarczego decyduje także poziom ubóstwa. Może być on mierzony różnymi wskaźnikami, m.in. tzw. indeksem HPI-2 obliczanym przez ONZ. Jako ciekawą z makroekonomicznego punktu widzenia alternatywę ukazano jednak miarę wskaźnika ubóstwa Okuna obliczanego poprzez zsumowanie stopy inflacji i stopy bezrobocia. Ranking państw Unii Europejskiej według tej miary w okresach 2000-2004 oraz 2005-2009 zaprezentowano w części czwartej. Całość zamknięto podsumowaniem, w którym zawarto syntetyczne wnioski z przeprowadzonych obserwacji
E2 strengths and transition radii difference of one-phonon 2+ states of 92Zr from electron scattering at low momentum transfer
Background: Mixed-symmetry 2+ states in vibrational nuclei are characterized
by a sign change between dominant proton and neutron valence-shell components
with respect to the fully symmetric 2+ state. The sign can be measured by a
decomposition of proton and neutron transition radii with a combination of
inelastic electron and hadron scattering [C. Walz et al., Phys. Rev. Lett. 106,
062501 (2011)]. For the case of 92Zr, a difference could be experimentally
established for the neutron components, while about equal proton transition
radii were indicated by the data. Method: Differential cross sections for the
excitation of one-phonon 2+ and 3- states in 92Zr have been measured with the
(e,e') reaction at the S-DALINAC in a momentum transfer range q = 0.3-0.6
fm^(-1). Results: Transition strengths B(E2;2+_1 -> 0+_1) = 6.18(23), B(E2;
2+_2 -> 0+_1) = 3.31(10) and B(E3; 3-_1 -> 0+_1) = 18.4(11) Weisskopf units are
determined from a comparison of the experimental cross sections to
quasiparticle-phonon model (QPM) calculations. It is shown that a
model-independent plane wave Born approximation (PWBA) analysis can fix the
ratio of B(E2) transition strengths to the 2+_(1,2) states with a precision of
about 1%. The method furthermore allows to extract their proton transition
radii difference. With the present data -0.12(51) fm is obtained. Conclusions:
Electron scattering at low momentum transfers can provide information on
transition radii differences of one-phonon 2+ states even in heavy nuclei.
Proton transition radii for the 2+_(1,2) states in 92Zr are found to be
identical within uncertainties. The g.s. transition probability for the
mixed-symmetry state can be determined with high precision limited only by the
available experimental information on the B(E2; 2+_1 -> 0+_1) value.Comment: 14 pages, 5 figures, submitted to Phys. Rev. C, revised manuscrip
Number statistics for -ensembles of random matrices: applications to trapped fermions at zero temperature
Let be the probability that a
-ensemble of random matrices with confining potential
has eigenvalues inside an interval of the real
line. We introduce a general formalism, based on the Coulomb gas technique and
the resolvent method, to compute analytically for large . We show that this probability scales for large
as , where is the Dyson index of the
ensemble. The rate function , independent of ,
is computed in terms of single integrals that can be easily evaluated
numerically. The general formalism is then applied to the classical
-Gaussian (), -Wishart () and
-Cauchy () ensembles. Expanding the rate function
around its minimum, we find that generically the number variance exhibits a non-monotonic behavior as a function of the size
of the interval, with a maximum that can be precisely characterized. These
analytical results, corroborated by numerical simulations, provide the full
counting statistics of many systems where random matrix models apply. In
particular, we present results for the full counting statistics of zero
temperature one-dimensional spinless fermions in a harmonic trap.Comment: 34 pages, 19 figure
Levy targeting and the principle of detailed balance
We investigate confined L\'{e}vy flights under premises of the principle of
detailed balance. The master equation admits a transformation to L\'{e}vy -
Schr\"{o}dinger semigroup dynamics (akin to a mapping of the Fokker-Planck
equation into the generalized diffusion equation). We solve a stochastic
targeting problem for arbitrary stability index of L\'{e}vy drivers:
given an invariant probability density function (pdf), specify the jump - type
dynamics for which this pdf is a long-time asymptotic target. Our
("-targeting") method is exemplified by Cauchy family and Gaussian target
pdfs. We solve the reverse engineering problem for so-called L\'{e}vy
oscillators: given a quadratic semigroup potential, find an asymptotic pdf for
the associated master equation for arbitrary
Pleiotropic effects of erythropoietin. Influence of erythropoietin on processes of mesenchymal stem cells differentiation
The article notes that рuman recombinant erythropoietin is characterised as a factor which stimulates differentiation and proliferation of erythroid precursor cells, and as a tissue protective factor. Erythropoietin is one of the most perspective humoral agents which are involved in the preconditioning phenomeno
Pharmacological modulation of cell functional activity with valproic acid and erythropoietin
Valproic acid (VA) is carboxylic acid with a branched chain, which is used as an antiepileptic drug. VA, which is an antiepileptic drug, is also a teratogen, which causes defects of a neural tube and an axial skeleton, although the mechanisms are not yet fully clear. It is shown that valproic acid reduces the intracellular level of oxygen active form
Comments on QED with background electric fields
It is well known that there is a total cancellation of the
\emph{factorizable} IR divergences in unitary interacting field theories, such
as QED and quantum gravity. In this note we show that such a cancellation does
not happen in QED with background electric fields which can produce pairs.
There is no factorization of the IR divergences.Comment: 14 pages, 1 figur
Multiplication law and S transform for non-hermitian random matrices
We derive a multiplication law for free non-hermitian random matrices
allowing for an easy reconstruction of the two-dimensional eigenvalue
distribution of the product ensemble from the characteristics of the individual
ensembles. We define the corresponding non-hermitian S transform being a
natural generalization of the Voiculescu S transform. In addition we extend the
classical hermitian S transform approach to deal with the situation when the
random matrix ensemble factors have vanishing mean including the case when both
of them are centered. We use planar diagrammatic techniques to derive these
results.Comment: 25 pages + 11 figure
Statistical mechanics of topological phase transitions in networks
We provide a phenomenological theory for topological transitions in
restructuring networks. In this statistical mechanical approach energy is
assigned to the different network topologies and temperature is used as a
quantity referring to the level of noise during the rewiring of the edges. The
associated microscopic dynamics satisfies the detailed balance condition and is
equivalent to a lattice gas model on the edge-dual graph of a fully connected
network. In our studies -- based on an exact enumeration method, Monte-Carlo
simulations, and theoretical considerations -- we find a rich variety of
topological phase transitions when the temperature is varied. These transitions
signal singular changes in the essential features of the global structure of
the network. Depending on the energy function chosen, the observed transitions
can be best monitored using the order parameters Phi_s=s_{max}/M, i.e., the
size of the largest connected component divided by the number of edges, or
Phi_k=k_{max}/M, the largest degree in the network divided by the number of
edges. If, for example the energy is chosen to be E=-s_{max}, the observed
transition is analogous to the percolation phase transition of random graphs.
For this choice of the energy, the phase-diagram in the [,T] plane is
constructed. Single vertex energies of the form
E=sum_i f(k_i), where k_i is the degree of vertex i, are also studied.
Depending on the form of f(k_i), first order and continuous phase transitions
can be observed. In case of f(k_i)=-(k_i+c)ln(k_i), the transition is
continuous, and at the critical temperature scale-free graphs can be recovered.Comment: 12 pages, 12 figures, minor changes, added a new refernce, to appear
in PR
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